New techniques for photographing the nerve fiber layer and analyzing threshold perimetry have proved potentially sensitive and specific indices of early to mild glaucomatous optic nerve damage. During the second phase of this longitudinal prospective study over 1600 eyes with ocular hypertension, 250 with early glaucomatous field loss and an additional 200-400 normal controls will continue to undergo annual re-examination including masked, detailed manual kinetic and static perimetry, automated threshold perimetry, clinical assessment, color stereoscopic photography of the optic nerve head and red-free photography of the nerve fiber layer for an additional four years. Analysis will determine the sensitivity and specificity with which NFL assessment alone and, or in combination with other ocular, systemic and demographic factors, and with which threshold perimetry can identify individuals at risk of glaucomatous nerve damage (by manual perimetry or changes in cup-disc parameters, the existing "gold standards") at annual intervals before such loss occurs. In addition, the natural history of ocular hypertension and correlative changes in these eyes will be established. Findings may result in new operative definitions of glaucoma for diagnostic and screening purposes, permitting effective and efficient intervention earlier in the disease process.